Trichina
2 of the 6 encyclopedias on this shelf carry an entry for Trichina. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
in zoölogy, a genus of Nematoidæ, established by Owen for the reception of the minute spiral flesh worm, T. spiralis, discovered in human muscle by Sir James Paget, in 1835, when a student at St. Bartholomew's Hospital, London. Mr. Hilton, of Guy's, had previously noticed gritty particles in human muscles, and recognized them as the results of parasites, afterward shown (by Owen) to be young trichinæ. The trichinæ met with in human muscle are minute immature worms, spirally coiled in small oval cysts, scarcely visible to the naked eye, measuring 1/78 inch in length and 1/136 inch in breadth. Sometimes the worms are not encysted, and measure 1/25 inch in length and 1/360 inch in breadth. The mature and reproductive trichinæ inhabit the intestinal canal of mammals, including man, and live for four or five weeks, attaining ability to reproduce on the second day of their introduction. The male is about 1/18 and the female 1/8 inch long. The eggs are hatched within the female, and as soon as the embryos are expelled they bore their way into the muscles, and there in about 14 days assume the form known as T. spiralis, often setting up trichiniasis. Thus the only way in which trichinæ can get into the human system is by being swallowed alive with pieces, of imperfectly-cooked muscle in which source of infection to man, as it is peculiarly liable to the presence of encysted trichinæ.
Aiton's Encyclopedia (1910)
tri-ki'na (plural, Trichinae), a small worm much dreaded as a parasite. It infests the muscles of the pig, rabbit, rat, and other animals. In an undeveloped condition each worm becomes surrounded by a small cyst or hardened envelope. When pork containing trichinae is eaten by man, the cysts are dissolved, the trichinae develop rapidly and breed in the alimentary canal , producing myriads of young within a few hours. These find their way into the walls of the intestines, and become encysted in the muscles. The irritation caused by their moving creates a loss of appetite and pains like those of rheumatism. The limbs swell as in dropsy; diarrhoea sets in. The results are always unpleasant and are sometimes fatal. A temperature of 167 degree F. kills the young trichinae. For this reason it is not considered safe to eat pork that has not been cooked thoroughly. The laws of Germany and other countries require that imported pork be examined under the microscope for trichinae. See Parasite ; Tapeworm
What Has Changed in the Last Century
Both accounts still describe the life cycle correctly, but the worm has been renamed: since Railliet's revision the parasite is Trichinella spiralis, not a member of Owen's genus Trichina, and molecular work from the 1970s onward showed it is not one species but a cluster of about a dozen, including the freeze-resistant Arctic form T. nativa. Aiton's 1910 advice that pork be examined under the microscope has largely been overtaken: American control came instead from banning the feeding of raw garbage to pigs under the Swine Health Protection Act of 1980, and confirmed human cases in the United States fell from thousands a year to roughly a dozen or so, most of them now traced to bear and other wild game rather than pork. Thorough cooking remains the advice, freezing kills the classic pork strain but not the Arctic one, and the drugs albendazole and mebendazole now give doctors something to offer patients that neither 1910 nor 1921 had.
Written for this edition, 2026.